Mac IIsi - SoG?

[Jules Richardson]

Can anyone confirm whether a Mac IIsi spits out sync-on-green (and only 
sync-on-green) or not? I've found mixed info on the 'net so far.

I've got a system here which makes encouraging startup noises, but isn't 
outputting any video to a VGA screen (adapter cable OK with my other Macs).

If it's SoG-only, well, there's my problem :-)  If it does output h/vsync 
like my other Macs then I need to look elsewhere (most likely nonsense 
NVRAM settings, I expect).

cheers

Jules